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Transposition of the Great Arteries
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Children’s heart conditions can’t be prevented, but a lot can be done to improve and often completely repair their hearts at any age. Thanks to advanced technology and the pediatric heart experts at the Nemours Cardiac Center (based at Nemours/Alfred I. duPont Hospital for Children), most children born with a heart problem — even newborns only hours or days old — can be quickly diagnosed and treated right when it matters the most. At the Cardiac Center, we specialize in early detection and repair of congenital heart defects (also often called, “congenital heart disease”).
If your child’s been diagnosed with transposition of the great arteries (or “TGA,” for short), we’re here to ease your concerns, answer your questions, and give your child the best possible chance for a healthy future.
There are two “great arteries” through which blood leaves the heart:
- the aorta, which normally originates from the left ventricle and carries oxygen-rich (“red”) blood out to the body
- the pulmonary artery, which normally originates from the right ventricle and carries deoxygenated (“blue”) blood to the lungs
In children with transposition of the great arteries, these two main arteries are in the opposite position: the aorta originates from the right ventricle, and the pulmonary artery originates from the left ventricle.
This results in two separate circulations of blood:
- The oxygen-rich (“red”) blood returning from the lungs enters the left atrium and left ventricle, and then is pumped back to the lungs through the pulmonary artery.
- The oxygen-poor (“blue”) blood returning from the body enters the right atrium and the right ventricle, and then is pumped back out to the body through the aorta.
This causes the baby to appear bluish (or “cyanotic”). Without a way for the oxygenated blood of the left ventricle to reach the aorta and, in turn, the rest of the body, the child may only live a few days.
Other Congenital Heart Defects That Are Part of TGA
There are different ways that the oxygenated blood may reach the aorta. As part of transposition of the great arteries a lot of children may also have other congenital heart defects:
- atrial septal defect (“ASD,” a hole in the wall between the right and left atria — the top two chambers of the heart)
- ventricular septal defect (“VSD,” an abnormal opening in the wall between the right and left ventricles)
The opening from either of those defects allows blood to flow between the right and left sides of the heart. Because the oxygen-rich and oxygen-poor blood will mix before being pumped out, the baby will still be blue, but usually less so, and is able to survive.
In other cases, there’s also a patent ductus arteriosus (or “PDA,” which allows the blood to flow between the pulmonary artery and aorta.
How Does the Heart Normally Work?
When your child has a congenital heart defect, there’s usually something wrong with the structure of the heart. In order to understand your child’s condition, it can help to know how the heart should work normally.
Learn More About Normal Cardiac Anatomy »
Nemours’ experts at KidsHealth.org also offer these helpful resources to help both you and your child understand how the heart works:
Many babies with TGA are diagnosed in utero (while still in the womb during pregnancy) during a fetal echocardiogram (or “echo”). Babies who aren’t diagnosed until after birth are likely to have signs and symptoms of heart failure and poor oxygen delivery to the body in the first minutes to hours after delivery.
Those symptoms would include:
- rapid breathing
- rapid heart rate
- poor ability to feed and lack of weight gain (also known as “failure to thrive”)
- bluish skin color (called “cyanosis”)
The severity of these symptoms depends on the mount of mixing of oxygenated and deoxygenated blood through the associated heart defects. Because the PDA usually closes in the hours after birth, babies may get sicker over that time period as there is less and less oxygenated blood getting out to the body.
In babies with low oxygen levels or poor oxygen delivery to the body, an echocardiogram (“echo”) will be performed to make the diagnosis. An echo is a completely safe and painless test that uses ultrasound (sound waves) to build a series of pictures of the heart.
Some babies also will need a cardiac catheterization to temporarily treat the low oxygen levels or to confirm the diagnosis and determine the exact location of the coronary arteries (the arteries that travel from the aorta to deliver blood to the heart muscle itself). Catheterization involves inserting a thin plastic, flexible tube (called a “catheter”) into an artery and vein that lead to the heart. Cardiac catheterization is done under sedation with local anesthesia or under general anesthesia, depending on your child’s age and condition.
All babies with TGA will need surgery, which our Nemours Cardiac Center heart surgeons usually perform in the first few days following birth. It’s common to delay the procedure for a few days until the baby has stabilized from delivery. During this period, if the oxygen levels in the body are too low, we may perform a cardiac catheterization procedure known as a “balloon atrial septostomy.” This involves enlarging the atrial septal defect (ASD) by inflating a balloon within it — this stretches the ASD and allows more oxygenated blood to mix and travel to the aorta and out to the body. A catheterization involves inserting a catheter (a tiny, hollow tube) through a vein (usually in the leg) leading to the heart. A balloon at the end of the catheter is then inflated to stretch the ASD open and improve the blood flow across the defect.
The corrective surgery for TGA is called the “arterial switch” operation. As the name implies, the two arteries (the pulmonary artery and aorta) are switched back into the appropriate location. This also involves moving the coronary arteries (the small blood vessels that supply oxygenated blood to the heart muscle itself) along with the aorta. At this time, if the child has any other defects (including an atrial septal defect, ventricular septal defect or patent ductus arteriosus) we repair those as well.
Historically a different procedure was done called the “atrial switch.” This procedure involved directing blood through the atria (the upper chambers of the heart) so that it switched sides. This way, the circulation was corrected and oxygenated blood from the lungs flowed out to the body, but the right ventricle was left pumping out the aorta and the left ventricle continued to pump to the lungs. Because the right ventricle is optimized to pump at lower pressures, in the years after the atrial switch procedure, this often resulted in heart failure. That’s because the right ventricle couldn’t handle the higher pressure of pumping out to the body. There was also a high risk of atrial electrical problems because of the large amount of suturing needed to change the direction of blood flow within the atria. For these reasons, we now perform the arterial switch in nearly all children.
Following the arterial switch procedure, the blood circulates through the heart, lungs and body. Some children will require additional operations or catheter-based procedures to treat narrowed pulmonary arteries. Narrowings (or “stenoses”) in the pulmonary arteries happen because the arterial switch procedure requires stretching the pulmonary arteries to bring them over top of the aorta (this is done because in children with transposition of the great arteries, the pulmonary artery started out directly behind the aorta, but needs to be switched to a position in front of it).
The coronary arteries may also develop narrowing as children grow, so our Nemours Cardiac Center cardiologists will often do tests as children get older to make sure the heart is getting plenty of blood flow, even during exercise. This might include a cardiac catheterization or exercise testing.
If your child has transposition of the great arteries, know that at the Nemours Cardiac Center we’re here to give your child the very best, most comprehensive and compassionate care. Our goal is to guide your family, from start to finish, through your child’s heart defect journey — and to help your child live the healthiest, most fulfilling life possible.
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Information for Patients
Outpatient Services and Inpatient Units: (302) 651-6660
After 5 p.m. and Weekends:
Cardiac Intensive Care Unit: (302) 651-6644
General Inpatient Unit, 2B: (302) 651-6690